Electric switch



July 4, 1944. H. LQVAN VALKENBURG ,35

ELECTRIC SWITCH Filed July 12, 1941 2 Sheets-Sheet l INVENTOR Herbmn LJ an kilfnlz /r y 4, 1.944. H. L. VAN IVALKENBURG 2,352,815

1 ELECTRIC SWITCH I Filed July 12, 1941 2 Sheets-Shet 2 E E IX: 'INVENTOR Y I Herman 1. X211 )filkenllny Passed July 4, 1944 Hermon L. Van Valkenburg, Wanwatosa; Winn assignorto Square B Company, Detroit, Mich,

a corporation of Michigan Application July12,l'1941, Serial No.'4oz,o5s I Claims. (01. zoo-1o) provide an electric switch having improved means for effecting quick make and break bf an electrical circuit. a

Another object of the present invention is to provide a limit switch in which a substantial emergency over-travel of the operator is permitted.

Another object of the present invention is to provide a limit switch having an improved form of operating handle.

Other objects, and features of the invention will be readily apparent to those skilled in the art from the specifications and appended drawings illustrating certain preferred embodiments in which: V

Figure 1 is a front elevational view of the limit switch according to the present invention.

Figure 2 is a side elevational view of the limit switch.

Figure 3 is a vertical sectional view taken on the line III-III of Figure 2.

Figure 4 is a vertical sectional view taken on Figure 9 is a vertical sectional view'taken on the line IX--IX of Figure 8. g

The switch, accordingto the present invention comprises a substantially rectangular casing I open at front and. back. A supporting plate 2 secured to the back of the casing, and a cover 3 mounted at the front thereof, seal off these openings. Gaskets disposed at the iunctures of the supporting plate 2 and mounting cover 3 with closes opening 5 and prevents interference from f the wiring with the contact assembly disposed within the opening. The contact block] rests j upon brackets l2 and I! provided by opposite" sides of enclosure I and spaced" from thefisupporting plate 2. Screws i4 passing through the contact block 4 secure the block to the brackets I! to maintain it in spaced relationjto'the supporting plate'l.

A movable contact assembly l5is disposed within the' opening 5 in the contact block and comprises an insulating block ii to which a sec- 0nd insulating block III is rigidly joined in any well known manner. The portion of block ill extending beyond the upper surface of block i6 is of an inverted T shape, the leg of which comprises a rectangular portion 31 which isof smaller outline than the outline of block I6, as

shown in Figure 3. The rectangular portion 33 is the rectangular body I provide an oil and dust tight enclosure. A contact block .4 havingan opening 5' therethrough is received within the V enclosure l'. Pairs of spaced contacts 6 and 1' are mounted'at opposite sides of the opening 5. Terminal studs '8 mount the stationary contacts 6 and I in place upon the contact block and serve to securelthe terminals of lead in wires to' the contact block. A transparent plastic guard plate I secured to the contact block 4 by a stud ried by the su portin Plate 2 is a -switching me adapted to engage opposite sides of'opning 5 .to thereby define the extent of movement of the contact assembly i5 within the opening 5. Block Ill is further provided with a rectangular opening l1 located substantially centrallyof that portion of block Ill above block IS. .A pair of spaced conducting plates l8 and I 9, having con- Ill to cooperate with the oppositely mounted stationary contacts 6 and i. The plates" l8 and i9 are mounted on block In by inserting them end wise through opening I! and then turningthem onedge so that'shoulder portions thereof closely embrace the lateral sides of block III as shown in Figure 6, which figure shows a section as passing through the opening l1. and between contact plates I8 and I9. A'spring 2| disposed between the conductingplates l8 and i9 normally maintains the plates in spaced relation-L ship and with their faces normally disposed against opposite deflningsurfaces of the opening l1. The pair of movable contacts are normally biased for bridging engagement' with stationary contacts 8 in amanner tobe hereinafter described. A flexible insulating lining 22 is wrapped about the contact block 4 and insulates the live parts and the wiring from the operating mechanism and the casing; I. Casing I'has an opening 23 provided'at the bottom thereof'andf leading into a wiring trough 24 disposed adja f cent to the contact block 4. This QOnStruction simplifies wiring df'tne contact block '9; Pivotally mounted upon,a pin,onpost,25

received within an opening provided by contact block l6 to effect a support for the movable contact assembly l and to maintain it within opening 5 in contact block 4. The pin 29 is of sufllcient length that contact assembly l5 when supported thereon will be in proper operating position within recess 5 to permit the ready engagement and disengagement of the movable contacts with the stationary contacts mounted at the sides of the opening 5. A stop pin 34 mounted upon the supporting plate 2 cooperates with the notch 3| to limit'the movements of the switch member 26 in opposite directions. Plvotally supported upon spaced pin members 35 and 36 provided by supporting plate 2 adjacent to the pivotal switch member 26 and on either side thereof are latch members 31 and 38 having ledges 39v and 4! thereon adapted to. engage respectively with catches Hand 26 of the switching member 26. A resilient wire 46 wound around the pins 35 and 36 and having the ends thereof engageable with the latch members 31 and 38 biases thesemembers for movement toward each other and toward the pivotal switching member 26 whereby the ledges 39 and 4| will be normally biased for engagement with the catches 21 and 28.

.An actuating shaft 42 passing through an opening provided in the top of casin l carries an operating member 43 at the inner extremity thereof and rigidly secured thereto for movement thereby. A pair of pins 44 and 45 are mounted upon the operating member 43 with the upper pin 44 passing through both the operating member 43 and the shaft 42. Carried at opposite sides of the operating member 43 are flat elongated lever members 46 and 41 each having a pair of openings therethrough adapted to receive the pins 44 and 45 to support the levers 46 and 41. A pair of conical springs 48 and 49 are mounted one at either extremity of the lower pin 45 and between a lever member and a cotter pin 5|. Both of the lever members 46 and 41 extend beyond the lower extremity of the operating member 43 and lie one at either side of the portion 32 of the pivotal switching member 26 and are engageable therewith for a purpose to be hereinafter described.

Rotatably secured to the operating member 43 and upon the upper face thereof is a generally L shaped member 52. A retaining stud 80 maintains member 52 on operating mechanism 43. A coil spring 53 having a spring guide pin 54 inserted in one end thereof is interposed between a leg of the L shaped member 52 and a slidable member 55 disposed against a side wall 56. The spring 53 normally biases the operating member 43 for movement in a clockwise direction as viewed in the drawings. This spring force is also exerted through lever 4'I-upon switching member 26 and throu h the switching member 26 upon the contact block l6 to normally bias movable contacts 20 into engagement with stationary member 52 may then be rotated 180 upon the' operating member 43 and made to face in the opposite direction. The slidable member 55 is then disposed against the opposite wall 51 of the casing and the coil spring 53 is fitted into posipair of spaced knurled discs 58 and 59, to each contacts 6. In this position, conducting plate I6 carrying contacts 26 will be spaced from the defining surface 10 of opening I! with which it 'is normally in contact, and is moved to this position against the bias of spring 2| to thereby provide a substantial contact pressure between of which there is secured as by riveting a plurality of elements 66 notched at opposite sides thereof to provide a shank portion 6|. Each of the assemblies comprising the knurled discs and the notched elements secured thereto are adapted to rotate upon the shaft 42. Mounted upon the shaft and between the movable assemblies are a group of notched elements 62 substantially similar to the notched elements 69, and also riveted together to form a unit. The notched elements 62 differ from elements 60 in that they are provided with key portions 63 adapted to be received within a longitudinal slot 64 provided in the shaft 42. Disposed about the notched elements 66 and 62 and lying between the knurled discs 58 and 59 are the resilient elements 65 having the ends thereof receivable within the oppositely disposed notches of the elements 60 and 62. A stud 55 threaded into the end of the shaft 42 maintains the knurled discs 58 and 59 and the elements contained therebetween in position upon the shaft. -An operating lever or handle 61 comprising a split hub portion 68 and an extended portion 69 carrying a roller H at an extremity thereof is adapted to actuate the shaft 42. The hub 68 is adapted to clamp upon the knurled discs 58 and 59 and to be tightened into fixed engagement therewith by a stud 12 whereby the discs and the operating lever 61 may move as a unit. Since the notched elements 50 are in engagement/with the resilient elements 65, movement of the discs 58 and 59 by the operating lever 61 will apply a force upon the resilient elements which force will be directed upon the notched elements 62, and since the elements 62 have a fixed engagement with the shaft 42 by reason of the key and slot connection therebetween, the applied force will act to rotate the shaft.

The operation of the device will now be described:

Limit switches are particularly adapted for use in the control circuits of automatic controllers for motors used in connection with machine tools, conveyors, hoists and similar equipment to stop the motor at its limits of travel'in one direction or both directions with provisions for overtravel protection in case the motor or machine travels past its normal limits.

Upon application of force to the roller by the drive shaft of the machine to be controlled to effect rotation of the operating arm 61, rotation of shaft 42 will be effected. As viewed in Figure 4, shaft 42 is to be rotated in a counterclockwise direction to effect a like movement of the operating member 43 against the bias of spring 53 and into engagement with lever 41 to carry it against latch 39 which, as shown, is in engagement with catch 28 of the pivotal switching member 26, to move the latch out of' engagement therewith. This movement of the operating member 43 will also efl'ect movement of the lever member 46, which will be carried by member 43 into engagement with portion 32 of the switching member 26 before lever 41 has disengaged latch 38 and while operating member .43 is moving lever 41 to disengage latch 38, lever aaoaem 46 is restrained from movement through this en gagement with switching member II, and switching member 28 is restrained from movement react through the lever 48 to quickly move the switch member 28 in a clockwise-direction to bring the opposite catch 21 into-position to engage with latch 31 which has been biased into latching position by the resilient element 40. This quick movement of the switch member 28 will effect a snap movement of the block I through its connection therewith by pin 29 to carry the contact elements 20 quickly out of engagement with their cooperating stationary concooperating with said pivotal levers to move said pivotal switching member with a snap action into engagement with a pivoted latch.

2. In an electric switch, an enclosure, a stationary contact mounted therein, a, movable contact, a pivotal switch member supported within said enclosure and movable to move said movable contact to engaged and disengaged positions, a pivot for said switch member, latch means mounted within said enclosure and being engageable with said pivotal switch member to retain said latter member in either of two positions, an operating member carried by said enclosure, a pivot for said operating member and spaced from said pivot for said switching member, a pair of movable members mounted on said operating member, said movable members being operable to alternately engage said pivotal switch member for movement thereof in opposite directions, and spring means carried by said operating member and at opposite sides thereof, said spring means tacts 8 and to carry movable contacts l0 into-en- 4 ,gagement with the oppositely disposed set of stationary contacts I. Stop 34 will engage the edge of notch SI of switch member 28 to limit the extent of movement of the switch member.

Upon the release of force from'the roller 12, the coil spring will act as a return spring to apply forceupon the operating member 43 for rotation'thereof in the reverse direction to effect reverseoperation of the parts and a snap movement of the contacts" and into their normal position as'viewed in Figure 3.

With the construction of the actuating means for the shaft 42 as above described, a substantial emergency overtravel of, the operating handle 61 is readily obtainable. If an unusual force or excess movement should be applied to roller H, the operating lever 6l will effect movement of shaft "to move the switch operating parts and the switch elements and will then 'move relative to the shaft 42 to take up the excess forcef The resilient elements 65 are adapted to be compressed by the notched elements 80 to allow this movement of the operating lever 61 relative to the shaft 42.

While certainpreferred embodiments of this a pivotal switching member supported within saidenclosure and movable to move said movable contact into 'and out of engagement with said stationary contact, means providing a pivot for said switching member, a pair of pivoted latches adapted to alternately engage. with said pivotal.

\ switching member, a spring means biasing said latches toward said pivotal ,member, an operating member carried by saidenclosure, a pivot for said operating mem'bei'and spaced from said pivot for said switching'member, a pair of pivotal levers mounted. on said operating member and at opposite sides'thereof, each of said pivotal levers being adapted to engage alternately with said pivotal switching member and with a pivotal latch to effect movement of each, and a pair of spring means, said spring means being disposed on opposite sides of said operating member and exerting their bias against said movable members for movement thereof to effect snapmovement of said pivotal switch member between said two positions.

3. In an electric switch, an enclosure, a stationary contact mounted therein, a movable contact, a switch member supported within said 'enclosure and movable to move said movable contact into and out of engagement with said stationary contact, a pair of pivoted latches mounted on the base of said enclosure and adapted to alternately engage the switch member to restrain movement thereof, an operating membercarried by said enclosure. spaced pin means fixed thereon, a pair of movable members supported by said pin means, said operating member being actuable to move said movable members into altemate engagement with said switch member,

and spring means operable to effect snap movement of said switch member when moving out of engagement with one pivoted latch and into engagement with the other.

4. In an electric switch, an enclosure, a base therefor, a stationary contact mounted thereon, a switch member supported on said base and being movable between two predetermined positions, a movable contact, a reciprocating member mounting said movable contact, said switch member having a pin and slot connection with said reciprocating member and being actuable to eifect movement of said movable contact into engaged and disengaged positions, a, pair of pivoted latches supported by said base and operable to engage alternately with said switch member to restrain said switch member in said predetermined positions, a pair of pivotal members, an

' operating member carried by said enclosure,

with said pivoted latches for alternate movement thereof out of engagement with said switch member, and spring means cooperating with said pivotal members to effect snap movement of Said switch memberoutof engagement with one pivoted' latch and into engagement with the other.

5; In an electric switch, an enclosure, 3. stationary contact mounted therein, a movable contact,

- a switch member pivotally supported on the base of said enclosure and movable between two positions of rest to efl'ect movement of said movable contact toward and away from said stationary contact, a pivot for said switch member, a pair of pivoted latches mounted on said base and adapted to engage, alternately, opposite sides of said switch member to restrain said switch member in said two positions of rest, a pair of movable rigid members disposed within said enclosure, operating means carried by said enclosure and upon a pivot spaced from said pivot for said switching member and operable to move the first of said movable rigid members into engagement with a first pivotal latch for movement thereof, and to move the se'cond movable rigid member into engagement with said switch member -to effect movement thereof when said first pivotal latch is moved to unlatching position.

6. In an electric switch, an enclosure, a stationary contact mounted therein, a movable contact, a switch member supported on the base of said enclosure and movable between two positions of rest to effect movement of said movable contact for cooperation with said stationary contact, a pivot for said switch member, a pair of latches pivotally supported on said base and adapted to alternately engage opposite sides of said switch member to restrain said switch member in said two positions of rest, a pair of movable rigid members supported within said enclosure, an

operating member carried by said enclosure and movement of said switch member, when said pivotal latch is moved to unlatching position.

7. In an electric switch, an enclosure, a stationary contact mounted therein, a movable contact, a switch member supported within said enclosure and actuable to move said movable contact into and out of engagement with said stationary contact, a pivot for said switch member, a pair of pivoted latches mounted on the base of said enclosure and adapted to engage alternately with said switch member to restrain the movement thereof, an operating member carried by said enclosure and upon a pivot spaced from said pivot for said switch member, a pair of rigid members mounted on said operating member and being movable relative'thereto, said operating member being operable to effect movement of said rigid members to alternately engage said switch member for movement thereof out of engagement with one pivoted latch and into engagement with the other, and spring means carried by said operating member and cooperating with said rigid members to effect snap movement of said switch member when moving out of engagement with one pivoted latch and into engagement with the other.

8. In an electric switch, an enclosure, a stationary contact mounted therein, a movable contact, a switch member supported within said enclosure and movable to effect engagement and disengagement of said movable contact with said stationary contact, a pivot for said switch member, a pair of pivoted latches mounted within said enclosure-and adapted to alternately engage opposite sides of said switch member to restrain movement thereof, an operating member carried by said enclosure and upon a pivot spaced from said pivot for said switch member, a pair of rigid members supported on said operating member and being movable relative thereto, said operating member being movable to move the first of said rigid members into engagement with a first pivoted latch for movement thereof and to move the second rigid member into engagement with said switch member to effect movement thereof when said first pivoted latch is moved to unlatching position, spring means mounted on said operating member and cooperating with said first rigid member to snap said switch member into engagement with said second pivoted latch upon said movement of the first pivoted latch to unlatching position.

9. In an electric switch, an enclosure, a stationary contact mounted therein, a movable contact, a switch member supported on the base of said enclosure and movable to move said movable contact into and out of engagement with said stationary contact, a pivot for said switch member, a pair of pivoted latches supported within said enclosure, spring means biasing said pivoted latches toward said switch member whereby said latches alternately may engage with said switch member, an operating member carried by said enclosure and upona pivot spaced from said pivot for said switch member, a second spring means acting to continually bias said operating member toward a predetermined position, a pair of rigid lever members movably mounted on said operating member and at opposite sides thereof, a pair of resilient means carried by said operating means and biased against said rigid lever members, said operating member being movable to move the first of said movable rigid levers to move a first pivoted latch against the bias of a resilient member and out of engagement with said switch member, and to move the second movable rigid lever to actuate said switch member with a snap movement into engagement with the second I pivoted latch, and spring means disposed within said enclosure and operative to effect movement of said switch member into reengagement with said first pivoted latch.

10. In an electric switch, a base member, an enclosing member, a contact block having an opening therein and supported within said enclosure and spaced from said base member, a stationary contact mounted on said contact block, a switching member supported by said base member and disposed between the contact block and the base member, a pivot for said switch member, a movable contact assembly disposed in said opening in said contact block, means providing a pin and slot connection between said movable contact assembly and said switching member, a pair of latching members mounted on the base member and on opposite sides of the switching member and engageable with said latter member to restrain movement thereof, an operating member supported by said enclosing member and upon a pivot spaced from said pivot for said switch member, a pair of rigid members pivotally supported on opposite sides of said operating member and being actuated thereby to move said pivoted latches alternately, and spring means mounted within said enclosure and operating to eifect snap movement of said switching member.

HERMON L. VAN VAIKENBURG. 

